Contact-Independent Antagonism of Ophidiomyces ophiodiicola, the Causative Agent of Snake Fungal Disease by Rhodococcus rhodochrous DAP 96253 and Select Volatile Organic Compounds

Abstract

Snake fungal disease (SFD), caused by the ascomycete Ophidiomyces ophiodiicola, has been associated with severe morbidity and mortality of numerous species of wild snakes in 15 US states. Accordingly, SFD was added to the horizon scan of global conservation issues in 2014. Due to the itinerant and secluded nature of many snake species, as well as the diversity of species impacted by SFD, estimating SFD-associated mortalities has been challenging. Regardless, the impacts have been shown to be significant in local and regional instances. Currently there is no known therapeutic or prophylactic for SFD. This study evaluated a potential biological treatment option for SFD that has shown promise in managing white-nose syndrome in bats, the bacterium Rhodococcus rhodochrous DAP 96253. R. rhodochrous was evaluated for in vitro contact-independent antagonism of O. ophiodiicola, with positive results. Additionally, synthetic volatile organic compounds (VOCs) associated with fungistatic soils were evaluated individually and in combinations to determine their potential for use as chemical control agents of SFD. In all cases an inhibitory effect was observed and statistically significant (p<0.05) radial growth inhibition was observed in several cases. The results presented in this study provide initial evidence for the in vivo evaluation of the potential of these agents to prevent or reduce the morbidity and mortality associated with SFD.

Biomimicry of volatile‐based microbial control for managing emerging fungal pathogens

“…), and Ophidiomyces ophiodiicola , the causative agent of snake fungal disease (SFD) of reptiles (Cornelison et al . ). Additionally, several antifungal susceptibility assays with synthetic formulations were conducted with previously discovered antifungal VOCs (Fernando et al .…”

“…Several microbially produced, antifungal VOCs have been identified from the scientific literature for their potential to be used for microbial control and disease management. Previous studies have demonstrated the ability of these microbially produced VOCs, as well as formulations comprised of several VOCs, to inhibit fungal mycelia growth, conidia viability, pigment production and virulence, when tested in the gaseous phase (Bruce et al 2003;Fernando et al 2005;Li et al 2010;Yuan et al 2012;Wang et al 2013;Cornelison et al 2014aCornelison et al , 2016Wu et al 2015;Toffano et al 2017). However, these studies have not attempted deep probing of soil communities and, therefore, suggest a tremendous untapped potential for the discovery of antimicrobials from fungistatic soil communities.…”

“…The body of literature comprising known microbially produced VOCs is numerous (Balis and Kouyeas 1968;Voisard et al 1989;Caccioni et al 1997;Gardini et al 1997;Bruce et al 2003;Ezra and Strobel 2003;Chuankun et al 2004;Fernando et al 2005;Zou et al 2007;Li et al 2010;Mitchell et al 2010;Garbeva et al 2011;Yuan et al 2012;Wang et al 2013;Weisskopf 2013;Cornelison et al 2014aCornelison et al , 2016Wu et al 2015;Toffano et al 2017). There exists a large number of chemical analogues that may also be potentially effective at eliciting microbial inhibition.…”

“…Indeed, this synergism has been observed with the inhibition of select fungal pathogens by synthetic VOC formulations of a microbial origin (Cornelison et al . , ). However, these positive effects do not negate the possibility of formulations increasing toxicity to the host or other nontarget organisms, and therefore, each formulation should undergo rigorous screening for undesirable effects.…”

“…, ), and Ophidiomyces ophiodiicola , the causative agent of snake fungal disease (SFD) of reptiles (Cornelison et al . ).…”